Update grass for parallel build

gprMax/fractals/fractal_surface.py

@@ -143,7 +143,7 @@ class FractalSurface:
 
         return surfacedims
 
-    def generate_fractal_surface(self):
+    def generate_fractal_surface(self) -> bool:
         """Generate a 2D array with a fractal distribution."""
 
         surfacedims = self.get_surface_dims()
@@ -199,6 +199,8 @@ class FractalSurface:
             - ((self.fractalrange[1] - self.fractalrange[0]) / fractalrange) * fractalmin
         )
 
+        return True
+
 
 class MPIFractalSurface(FractalSurface):
     def __init__(
@@ -218,7 +220,7 @@ class MPIFractalSurface(FractalSurface):
         self.comm = comm
         self.upper_bound = upper_bound
 
-    def generate_fractal_surface(self):
+    def generate_fractal_surface(self) -> bool:
         """Generate a 2D array with a fractal distribution."""
 
         if self.xs == self.xf:
@@ -247,7 +249,7 @@ class MPIFractalSurface(FractalSurface):
             self.start = np.minimum(self.start, self.upper_bound)
             self.stop = np.maximum(self.stop, 0)
             self.stop = np.minimum(self.stop, self.upper_bound)
-            return
+            return False
         else:
             # Create new cartsesian communicator for the Fractal Surface
             comm = self.comm.Split(color=color)
@@ -262,8 +264,17 @@ class MPIFractalSurface(FractalSurface):
         # Check domain decomosition is valid for the Fractal Volume
         if all([dim > 1 for dim in self.comm.dims]):
             raise ValueError(
-                "Fractal surface must be positioned such that its MPI decomposition is 1 in at least"
-                f" 1 dimension. Current decompostion is: {self.comm.dims}"
+                "Fractal surface must be positioned such that its MPI decomposition is 1 in at"
+                f" least 1 dimension. Current decompostion is: {self.comm.dims}"
+            )
+
+        # Check domain decomosition is valid for the Fractal Volume
+        if len(self.grass) > 0 and self.comm.size > 1:
+            raise ValueError(
+                "Grass cannot currently be split across multiple MPI rank. Either change the MPI "
+                " decomposition such that the grass object is contained within a single MPI rank,"
+                " or divide the grass object into multiple sections. Current decompostion is:"
+                f" {self.comm.dims}"
             )
 
         surfacedims = self.get_surface_dims()
@@ -445,3 +456,5 @@ class MPIFractalSurface(FractalSurface):
         logger.debug(
             f"Generated fractal surface: start={self.start}, stop={self.stop}, size={self.size}, fractalrange={self.fractalrange}"
         )
+
+        return True

gprMax/user_objects/cmds_geometry/add_grass.py

@@ -173,14 +173,22 @@ class AddGrass(RotatableMixin, GeometryUserObject):
         else:
             raise ValueError(f"{self.__str__()} dimensions are not specified correctly")
 
-        surface = FractalSurface(xs, xf, ys, yf, zs, zf, frac_dim, seed)
+        surface = grid.create_fractal_surface(xs, xf, ys, yf, zs, zf, frac_dim, seed)
         surface.ID = "grass"
         surface.surfaceID = requestedsurface
 
+        # Create grass geometry parameters
+        # Add grass to the surface here as an MPIFractalSurface needs to
+        # know if grass is present when generate_fractal_surface() is
+        # called
+        g = Grass(n_blades, surface.seed)
+        surface.grass.append(g)
+
         # Set the fractal range to scale the fractal distribution between zero and one
         surface.fractalrange = (0, 1)
         surface.operatingonID = volume.ID
-        surface.generate_fractal_surface()
+        if not surface.generate_fractal_surface():
+            return
         if n_blades > surface.fractalsurface.shape[0] * surface.fractalsurface.shape[1]:
             raise ValueError(
                 f"{self.__str__()} the specified surface is not large "
@@ -220,10 +228,6 @@ class AddGrass(RotatableMixin, GeometryUserObject):
                 surface.fractalrange[0], surface.fractalrange[1], size=1
             )
 
-        # Create grass geometry parameters
-        g = Grass(n_blades, surface.seed)
-        surface.grass.append(g)
-
         # Check to see if grass has been already defined as a material
         if not any(x.ID == "grass" for x in grid.materials):
             create_grass(grid)

reframe_tests/tests/test_geometry.py

@@ -168,7 +168,8 @@ class TestTriangleGeometry(GprMaxRegressionTest):
 @rfm.simple_test
 class TestAddGrassMpi(MpiMixin, TestAddGrass):
     tags = {"test", "mpi", "geometery", "fractal", "surface", "grass"}
-    mpi_layout = parameter([[1, 2, 2], [3, 1, 3], [4, 1, 4]])
+    mpi_layout = parameter([[2, 2, 2]])
+    model = parameter(["add_grass_small"])
     test_dependency = TestAddGrass